Eric Tischer's VW Passat EV Conversion

30,255 miles without gas since 4/18/2009

2011-08-02 Getting the Passat tach working has been a bit of a challenge. The needle movement is done with a stepper motor. I bought an Arduino and a stepper motor card to drive the stepper motor. I had just enough I/O left on the Ardunio to run an LCD display. The LCD displays pack voltage, and the lowest voltage reading (sag) over the last 30 seconds.

2011-08-02 Air Conditioning install is complete! Check out the A/C link on the left for the full details.

2011-07-01 Considering I removed the engine wiring and ECU, I never have much hope of having a working speedometer. Thanks to a random email from an Aussie who is also converting his 2001 VW, my speedo and odometer are working! Check out the awesome MPGs.

Encoder kit for the Ford Siemens motor 2011-01-29 I'm finally adding an encoder to my motor. The motors built in encoder was only 64 lines, and this was too low for my inverter to read. The encoder will provide accurate speed feedback at low RPMs, which should improve off the line torque. The kit consists of an expanding coupling which is inserted into the hollow shaft of the motor. The encoder mount slides into the bearing journal of the rear cover. A signal conditioner converts the encoders single ended output to differential outputs for long cable runs. My encoder setup doesn't use bearings so it won't restrict the max rpm of motor. The encoder disc is 250 lines.

Fill'er up! 2010-11-15 Solyndra installs EV charging stations. I can charge at 5.5 miles per hour at work, and up to 12 miles per hour at home (using 230v). This means, after driving 24 miles, I can recharge in 2 hours. I recently made a J1772 adapter so I can charge at 208V from public charging stations.

New Top speed: 105 mph 2011-11-14 Top speed was tested on flat ground in 5th gear. Current from the battery was 216 amps, or roughly 90 hp. The cooling upgrade to my inverter was the biggest factor associated with increasing top speed. My hill climbing top speed is up too. I can maintain 75mph climbing a 6% grade (south bound Sunol grade in Sunol, California). Current from the battery was 235A.

"Fuel" gauge 2010-10-28 Today I added a LinkPro battery monitor (equivalent to a gas gauge). The LinkPro calculates Amp-hours and "% full", letting me know how much charge is left in my battery pack. 1 amp hour lets me drive about 1.2 miles. My battery is 100 amp hours, so I should have 100 mile range with some reserve capacity. The LinkPro also displays Amps, this lets me know how quickly I'm draining my batteries (or how long it will take till they are fully charged if I am charging). There is more info about the LinkPro in the charger section.

Battery Management installed 2010-10-04 I spent about 30 hours installing BMS on my car over the weekend. I added a new Battery Management link in the navigation window. The cells located under the car (where the gas tank used to be), behind the seat, and in the spare tire well, were impossible to access. I installed some din-rail mounted fuse holders in an easy to access location, now I can monitor and balance the cells remotely. The cell wiring is protected with 3 amp fuses (purple). I made some plastic spacers so the BMS boards could be rigidly stacked.

Update 2010-09-20 I upgraded the heat sink in my inverter to a six row chill plate. The IGBT pack is now mounting directly to the copper cooling lines for maximum heat transfer. My homebuilt inverter now has triple the cooling power, and runs about 50 degrees F cooler!

Update 2010-09-11 Here are some of the minor improvements I've made over the last six months. I discovered the 2002 model Passats have a rain cover, but my 2001 Passat doesn't. I bought the parts and installed the cover. This really cleans things up! I built a shelf above my batteries, this is where my BMS will be mounted. My battery charger exhausts quite a bit of hot air, and since the charger is sealed in the trunk, this heat has no where to escape. I added some blowers just above the chargers exhaust. They suck the hot air, and blow it out of the trunk though a hole behind the rear license plate. The fans are thermostatically controlled so they typically only run on hot days. They are also powered from a small power supply which is powered by 115vac or 230vac from the charging plug. This supply also energizes an interlock relay which prevents me from driving with the charging cord plugged in.

Update 2010-05-29 I made some major improvements to the inverter and knocked two seconds off my 0-60 time! Here is a graph showing 0-60 in 14 seconds (6800rpm) only using 2nd gear. DC Bus Voltage (0-400 VDC) (The DC voltage sag is indicative of battery current, every 10v sag = 100A). Motor RPM x 20 (0-8000 RPM) Motor current (0-400 Amps/Phase) I find myself driving 75-80mph on my commute home now! There is much less traffic since NUMMI has closed. At 100A, the car maintains 78mph, compare this to 60 amps at 60mph. My range at 60mph should be 100 miles. At 78mph it looks like my range gets reduced to about 75 miles. I got a $2400 tax credit which covers 10% of the cost of converting the car to electric. My insurance company required me to get an appraisal for my car after I told them I just installed a twelve thousand dollar battery pack. Their appraiser estimated the cars value at $52k! At first I was upset I had to deal with the hassle and expense of an appraisal, but if anything ever happened to the car, the appraisers 45 page report clearly shows why it is worth more than blue book.

Update Got the car officially weighed, it is 3700 lbs.

Charging Station

I wired in a GFI and timer to take advantage of our $0.03/kWhr electricity rate after midnight. Electricity during peak hours is 9x more expensive! Charging from midnight to 7am brings my cost per mile down to 0.5 cents per mile ( I charge at work for free 50% of the time). Cost to drive 1000 miles in the Electric car = $5 Cost to drive 1000 miles in my Land Rover = $244 (plus oil changes, tune ups, fixing oil leaks...)

Update 2009-12-31 My battery shipment was delayed, all in all it took 3.5 months for them to arrive. Since I had nothing better to do with the car, I made some super awesome battery racks. I added a "Battery Upgrade" link to the left window frame. I also rotated my motor 90 degrees to put the junction box and coolant fittings on the side, this allows the battery rack to sit 2" lower in the car.

Update (car had old lead acid battery pack) 2009-07-31 After 41 days of waiting I finally got my carpool stickers!! It's hard to tell, but I also installed my custom wound rear springs. These springs are designed to support an additional 500lbs, and my car sits perfectly level now.

Update (car had old lead acid battery pack) Offical weight of my Passat (including driver) is 4200 lbs Non-official dyno reading of 83.5hp (running daily driver mode, 95% power) 2009-07-14 Results from this test were within 1% of the average. The average was made up of 10 runs 0-60 in both directions. There are other torque/current profiles I have created which produce higher hp numbers, but 95% current limit has proven reliable, and that is likely what will be used for production. This is horsepower measured at the wheel, which includes drivetrain losses.

Update 2009-04-28 There is an article about my car in Wired magazine.